Does VIN autofill from the license plate lift homepage conversion?
The mobile homepage form asked visitors for their VIN. We hid the VIN field and filled it in from the license plate number. Conversion fell 2.5% over 15 days, not a conclusive result, and we paused the test.
Not significant Mobile 15 days Not called
The hypothesis
By hiding the VIN field and filling it in from the license plate number, we will cut the effort the form takes, resulting in more visitors reaching the confirmation step.
Visitors came to renew a vehicle registration, and the homepage form asked for a VIN. Many people do not have their VIN at hand, so the field could stop them before they got started.
The license plate number is easier to find. Filling the VIN in from the plate would remove that roadblock and leave fewer fields to complete.
What we changed
We hid the VIN field and filled it in from the license plate.
The variation removed the VIN field from the mobile homepage form. Visitors entered their license plate number, and the VIN was filled in from it in the background. The rest of the form and the page stayed the same. A desktop version ran at the same time.
- VIN field hidden on the mobile form
- VIN filled in from the license plate
- Rest of the form unchanged
The result
Conversion fell 2.5% on mobile over 15 days, not a conclusive result.
Early results looked strong, mostly on desktop. On mobile, the later funnel steps did not see the same lift. After 15 days, mobile conversion was down 2.5%, which did not reach our confidence bar.
The desktop version was up 2.7%, also not conclusive. Weighing that small lift against the cost of the change, we paused both tests.
What we would do next
Retest VIN autofill alongside other form shortcuts.
Hiding the VIN removed a field, but it did not move mobile visitors through the form, and the desktop gain was too small to pay for the change. We tested filling in the ZIP code from location next, with a plan to bring VIN autofill back in a later round.